In disc drives, digital data is written to and read from the surfaces of one or more discs. Read and write operations are performed through a transducer which is typically carried on a slider body. The slider and the transducer are sometimes collectively referred to as a data head, and typically a single data head is associated with each data storage surface. The communication to and from the data heads is performed by a read/write preamplifier. High storage-capacity disc drives typically have a large number of data heads and thus have multiple read/write preamplifiers. Each read/write preamplifier typically drives a plurality of individual data heads, usually on a multiplexed basis. Typical read/write preamplifiers have a variety of fault detectors which monitor the operation of the preamplifier and send a fault signal to the drive controller if a fault condition occurs.
In a typical disc drive, an actuator operates in a servo system. The actuator moves the data head radially over the disc surface for track seek operations and holds the transducer directly over a track on the disc surface for track following operations. A servo controller samples the position of the data heads relative to some reference point and generates an error signal based upon the difference between the actual position and the reference position. This error signal is then used to drive the data head to the desired reference point. In one type of servo system, each track on a disc includes servo position information in a block of data referred to as a header. As the trend in the disc drive industry is to increase the efficiency of storing the user's data, the so-called "headerless" track formats are being considered. These formats allow more of the disc space to be used for the user's data, as opposed to servo and track information. However, these headerless track formats raise additional difficulties for guaranteeing data integrity, as the header formerly served to ensure that data was being written to the intended track.
The present invention provides a means of improving data integrity and offers other advantages over the prior art.